1. Field of the Invention
This invention relates generally to electronic devices, and more particularly to thermal management and electromagnetic interference shielding for electronic devices.
2. Description of the Related Art
The form factors and thicknesses of handheld computing devices, such as smart phones, tablet computers and e-book readers, have been trending downward for some time. At the same time, the complexity and power dissipation of these devices has been increasing. There is ongoing user demand for devices that are not only smaller form factor for greater portability but also powerful enough to handle video and other computing intensive tasks. The provision for significant computing power in a relatively small form device often translates into the need for significant thermal management of the heat dissipating devices. The inclusion of electromagnetic interference (EMI) sensitive components, such as radios, into these devices has introduced challenges in EMI shielding in addition to thermal management. Onboard components, such as processors, generate electromagnetic emissions with electric field (E-field) and magnetic field (H-field components) that interfere with the operations of the onboard radios. The near field effects created by the tight spacing in small form electronic devices present shielding challenges.
One common solution used to transfer heat from a processor in a small form device includes the use of a thermal spreader that is in thermal contact with the processor. The heat spreader is in turn, in thermal contact with a heat exchanger via a heat pipe or other structure. The heat exchanger often includes an air mover such as a fan. One example of such a conventional device is the model LE1700 manufactured by Motion Computing, Inc. The LE1700 includes a very thin fan that drives air flow through metal fins that are connected thermally to a thermal spreader mounted to the microprocessor and by way of a heat pipe. The hot air then goes to the external ambient by way of a small vent. An Acer model Iconia is another conventional example.
In many conventional designs, EMI shielding and thermal management have been treated as discrete problems and addressed with discrete solutions. One conventional EMI shield design utilizes a shell that is placed over a processor on a system board. The shell is connected to the system board ground plane, but is not in thermal contact with the processor and thus does not provide thermal management.
The present invention is directed to overcoming or reducing the effects of one or more of the foregoing disadvantages.